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Light I.Electromagnetic Radiation  EM Radiation  EM Spectrum  Types of EM Radiation.

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Presentation on theme: "Light I.Electromagnetic Radiation  EM Radiation  EM Spectrum  Types of EM Radiation."— Presentation transcript:

1 Light I.Electromagnetic Radiation  EM Radiation  EM Spectrum  Types of EM Radiation

2 A. EM Radiation  Electromagnetic Radiation  transverse waves produced by the motion of electrically charged particles  does not require a medium  speed in a vacuum = 300,000 km/s  electric and magnetic components are perpendicular

3 A. EM Radiation  Photons  tiny, particle-like bundles of radiation  absorbed and released by electrons  energy increases with wave frequency

4 B. EM Spectrum long low f low energy short high f high energy

5 C. Types of EM Radiation  Radiowaves  lowest energy EM radiation

6 C. Types of EM Radiation  Radiowaves  FM - frequency modulation  AM - amplitude modulation  Microwaves  penetrate food and vibrate water & fat molecules to produce thermal energy

7 C. Types of EM Radiation  Infrared Radiation (IR)  slightly lower energy than visible light  can raise the thermal energy of objects  thermogram - image made by detecting IR radiation

8 C. Types of EM Radiation  Visible Light  small part of the spectrum we can see  ROY G. BIV - colors in order of increasing energy ROYG.BIV redorangeyellowgreenblueindigoviolet

9 C. Types of EM Radiation  Ultraviolet Radiation (UV)  slightly higher energy than visible light  Types: UVA - tanning, wrinkles UVB - sunburn, cancer UVC - most harmful, sterilization

10 C. Types of EM Radiation  Ultraviolet Radiation (UV)  Ozone layer depletion = UV exposure!

11 C. Types of EM Radiation  X rays  higher energy than UV  can penetrate soft tissue, but not bones  Used to be used to size shoes before harmful affects were known.

12 C. Types of EM Radiation  Gamma rays  highest energy EM radiation  emitted by radioactive atoms  used to kill cancerous cells Radiation treatment using radioactive cobalt-60.

13 CHECK UNDERSTANDING 11. A light wave is an electromagnetic wave that has both an electric and magnetic component associated with it. Electromagnetic waves are often distinguished from mechanical waves. The distinction is based on the fact that electromagnetic waves ______. aa. can travel through materials and mechanical waves cannot bb. come in a range of frequencies and mechanical waves exist with only certain frequencies cc. can travel through a region void of matter and mechanical waves cannot dd. electromagnetic waves cannot transport energy and mechanical waves can transport energy ee. electromagnetic waves have an infinite speed and mechanical waves have a finite speed

14 Check Understanding  a. Which region of the electromagnetic spectrum has the highest frequency?  b. Which region of the electromagnetic spectrum has the longest wavelength?  c. Which region of the electromagnetic spectrum will travel with the fastest speed? GAMMA RAY RADIO WAVE All waves have the same speed which depends on the medium

15 Check Understanding  a. Which color of the visible light spectrum has the greatest frequency?  b. Which color of the visible light spectrum has the greatest wavelength? VIOLET RED

16 Light II. Light and Color  Light and Matter  Seeing Colors  Mixing Colors

17 A. Light and Matter  Opaque  absorbs or reflects all light  Transparent  allows light to pass through completely  Translucent  allows some light to pass through

18 B. Seeing Colors  White light  contains all visible colors - ROY G. BIV  In white light, an object…  reflects the color you see  absorbs all other colors REFLECTS ALL COLORS ABSORBS ALL COLORS

19 B. Seeing Colors  The retina contains…  Rods - dim light, black & white  Cones - color red - absorb red & yellow green - absorb yellow & green blue - absorb blue & violet Stimulates red & green cones Stimulates all cones Video: How Cones and Rods Work

20 B. Seeing Colors  Color Blindness  one or more sets of cones does not function properly Test for red-green color blindness.

21 C. Mixing Colors  Primary light colors  red, green, blue  additive colors  combine to form white light View Java Applet on primary light colors.Java Applet on primary light colors  EX: computer RGBs

22 C. Mixing Colors  Filter  transparent material that absorbs all light colors except the filter color View Java Applet on filters.Java Applet on filters

23 C. Mixing Colors  Pigment  colored material that absorbs and reflects different colors  Primary pigment colors  cyan, magenta, yellow  subtractive colors  combine to form black  EX: color ink cartridges

24 C. Mixing Colors LightPigment When mixing pigments, the color of the mixture is the color of light that both pigments reflect.

25  Bill Nye Explains Color Bill Nye Explains Color


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